National and California treatment costs to comply with potential hexavalent chromium MCLs

Abstract

The anticipated hexavalent chromium [Cr(VI)] drinking water standard in California and related national attention has sparked a public policy debate about potential regulatory action, but to date that debate has been lacking in a sound appreciation of the cost implications for Cr(VI) treatment of drinking water. This article imputes national and California‐specific cost implications from low‐level Cr(VI) treatment goals (1, 2, 5, 10, and 20 μg/L) for community water systems based on the best available scientific information regarding occurrence and demonstrated treatment technologies. The annual costs for a national 10‐μg/L Cr(VI) standard would range from $0.55 billion to $5.1 billion/year, substantially higher than those for previous drinking water regulations. The results reported here provide a guide to future cost analyses using the third Unregulated Contaminants Monitoring Rule and other occurrence databases and outline the key information gaps that will need to be addressed in order to arrive at a cost analysis sufficient to support sound regulatory decisions.